I'm running a game where the PCs discover that they're actually Fae. Obviously this isn't strictly canonical - Fae in CtL leave fetches in place of children, not their own young - but I'm otherwise trying to stay with the source material as much as possible.

The book says that "the human mind [...] seems intrinsically incapable of comprehending the vast paradoxical nature of [Fairie]", but as True Fae the PCs should be able to understand it a lot better. So, how do I describe the world such that the PCs can function there while still conveying something that the players themselves should be incapable of comprehending?

This seems like a terrible idea, but I like to push the boundaries and see what I can make work.

In the end the PCs fortunately didn't spend too much time in the Fae world, but for when they were there I mostly just ran it as Equinox Road describes for mortals (which is considerably less paradoxical than the core book suggests), but explaining the basic rules of a realm as they became relevant rather than leaving them to work those things out for themselves. Also, only one of them ever truly shed his mortal form and doing so left title-less and trapped in the (surprisingly ill-described) weakened actor form, which meant it always made sense that they saw things from am much more mortal-based perspective anyway.

Possibly I kind of wussed out on the idea a little bit by keeping them grounded that way, but the 'True Fae in Faerie' was never the goal of the campaign; it was more an eventuality I wanted to be prepared for if it came up. The players all said they enjoyed the campaign though, so I call that a win.

sorta off topic but an episode of radiolab discussed how even with the physical ability to perceive some things, unless we know/need to know it can go unnoticed. (ie: the color blue in african tribes) radiolab.org/2012/may/21/perfect-yellow
–
Colin DJul 5 '12 at 13:51

Have you (or any future readers of this comment) by any chance read/used it enough to give a brief summary of how they go about it?
–
AceCalhoonFeb 1 '12 at 21:47

I acquired a copy of this book and it definitely has some useful ideas. I'll try to come back and edit some kind of summary into this answer once I've had a bit more time to read.
–
BraibaFeb 10 '12 at 19:08

Just a wild guess about how I'd go about this: Use a lot of synesthesia and sense-verb-mixture that makes only partial sense.

An example: The street's singing like a steam train departing for the paleness of the Moon when you exit the building of the bank. It's apparently happy to be trodden by feet as salty as yours - though you couldn't tell for how far its happiness will last. Coming towards you round a corner there's already the metal neighing of the police cars, and you suddenly feel you've gotta hurry with your radiant bags unless you want to spend the night building a hot stairway to the North Pole.

I'm not saying it's gonna be easy and I would use only bits of this and then tell the players their PCs, attuned to the mortal world and currently still bound to/by it (by memories, feelings etc) simply can't get loose enough to fully come to their fae senses and understanding... but it's up to you.

Of course, I'd require the players to communicate their PCs actions and such similarly to be able to function as real fae for a while.

True Fae are, by definition completely alien and uncomprehendable to human mind. Which means, by definition they make very poor player choice. The true Fae do not work by the standard system of motivations that we would think of as humans. Their entire existence is defined by a complex set of rules and agreements.

Two possible solutions would be:

1) Your characters are Fae touched, or Changlings, but part of the process involved removing their memories. So they can discover their true nature. (Or they themselves could be the fetch, not knowing that their is this weird world hunting them down).

2) They could be True Fae but do to some bizarre bargain has been forced to "humanize" themselves for a period of time. In this case the characters would be effectively Avatars of their former selves, and could be played as Changlings at Wyrd 8 or so.

Either way the world remains the same, but their perceptions of it becomes far far different. Change your focus onto things that would be important given their unique perceptions. Maybe an ally cat is far more interesting then the car hurtling towards them, so you neglect to mention the car until its almost too late.